jplante4 wrote:
I currently have 4 12 volt Napa "deep cycle" marine/RV battries that I'm estimating at about 200 AH for all 4. The new arrangement should get me to around 800 AH.
As long as you have the height and footprint for the new batteries you'll have more AH but not what you suggest.
Most likely you currently have about 4x80=320AH with the 4 parallel batteries. 2 6V in series doubles the voltage but not the amps. So you will have about 2x232=464AH for the 4 series parallel batteries.
Many would also suggest more than 200W solar but try it and see how it works out.